Calcium/vitamin D not effective for secondary prevention of fracture
Grant AM, Avenell A, Campbell MK, et al, for the RECORD Trial Group. Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (Randomised Evaluation Of Calcium OR vitamin D, RECORD): a randomised placebo-controlled trial. Lancet 2005; 365:1621-1628.
Porthouse J, Cockayne S, King C, et al. Randomised controlled trial of supplementation with calcium and cholecalciferol (vitamin D3) for prevention of fractures in primary care. BMJ 2005; 330:1003-1006.
* Clinical Question
In older people who have already experienced an osteoporosis-related fracture, does vitamin D, calcium, or the combination prevent secondary fractures?
* Bottom Line
The combination of calcium 1000 mg and vitamin D3 800 IU was ineffective in preventing fractures in 2 studies enrolling a total of more than 8500 participants, almost all of whom were female and aged at least 70 years who either had a previous osteoporotic fracture or were at high risk. The dose of calcium is lower than the 1500 mg commonly recommended and used. These results conflict with a meta-analysis that found that the combination therapy reduced fracture rate, including hip fracture, in older patients who have not had a previous hip or nonvertebral fracture (JAMA 2005; 293:2257-2264). (LOE=1b)
Study Design
Randomized controlled trial (double-blinded)
Allocation
Concealed
Setting
Population-based
Synopsis
wo studies, both conducted in the United Kingdom, studied the effect of calcium and vitamin D. In the first study, the researchers recruited 5292 participants following treatment for a fracture. Most (85%) were white women, all were at least 70 years old and ambulatory, and all had a previous osteoporotic fracture, on average 1 month before entering the study. Approximately 20% of the participants were taking a thiazide diuretic, which blocks calcium excretion.
Using concealed allocation to avoid selective enrolling of patients into a specific treatment, the researchers randomly assigned patients to receive 800 IU daily oral vitamin D3, 1000 mg calcium, the combination of both, or placebo. The patients took their assigned treatment for at least 2 years. Overall, new fractures occurred in 13.0% of the participants; hip fracture, the more clinically relevant outcome, occurred in 3.4% of participants.
Compliance was not good in the study; by 2 years only half the patients were still taking their assigned treatment, and the 2 groups taking calcium had significantly higher noncompliance, with only 42% still taking their assigned treatment at 2 years. The results were analyzed using intention-to-treat, which leaves patients in their assigned groups even if they dropped out of the study or were not compliant. Neither calcium supplementation, vitamin D, nor the combination was effective in decreasing the rate of overall fractures or hip fractures. Compliant patients also did not have lower fracture rates, though the number of patients (508) taking both vitamin D and calcium may not have been large enough to find a difference if one existed.
In the second study, the researchers surveyed general practices across England to find women aged 70 years or older who had either a previous fracture or at least 1 risk factor: low body weight, maternal history of fracture, smoking, or poor/fair health. The 3314 women were randomized, using concealed allocation, to receive either placebo or the combination of calcium 1000 mg and vitamin D3 800 IU. Over a median follow-up of slightly more than 2 years, 4.3% of women experienced a fracture, and 0.7% experienced a hip fracture. Similar to the first study, there was no difference in fracture rates or hip fracture rates with treatment, either overall or in patients who were compliant.
Do calcium antagonists help patients with angina pectoris?
For several years the treatment of angina has been based on combinations of nitrates, beta blockers, and calcium antagonists. In the mid 1990s, there was concern about the long-term safety of calcium antagonists. Poole-Wilson and colleagues studied the effect of the long-acting calcium agonist nifedipine on patients with stable angina pectoris in the ACTION study.
More than 7,600 patients with stable angina pectoris from 291 treatment facilities in 19 countries were recruited for the study. Patients were 35 years or older and required oral or transdermal therapy to prevent or control symptoms. Reasons for exclusion included left ventricular ejection fraction less than 40 percent, overt cardiac failure, major cardiovascular event or intervention in the previous three months, significant cardiac valvular or pulmonary disease, and unstable insulin-dependent diabetes mellitus.
Nifedipine or placebo was added to current therapy depending on randomization. The initial dose of nifedipine was 30 mg daily. If tolerated, this was increased to 60 mg daily within six weeks. Other medications were continued at the discretion of the treating physician except for calcium antagonists, cardiac glycosides (except for supraventricular arrhythmia), positive inotropic agents, antiarrhythmic agents in classes I or III other than amiodarone (Cordarone) or sotalol (Betapace), cimetidine (Tagamet), antipsychotic agents, antiepileptic drugs, and rifampin (Rifadin). Randomization was made following baseline assessment that included a full medical history, echocardiography, blood pressure assessment, and classification into a New York Heart Association (NYHA) category. At each six-month follow-up, clinical assessment included NYHA status, vital signs, and monitoring for adverse effects. The study assessed survival without a major cardiovascular event. This was measured as time to occurrence of acute myocardial infarction, refractory angina, new overt heart failure, debilitating stroke, peripheral revascularization procedure, or death from any cause. The primary combined endpoint was death from any cause, acute myocardial infarction, and debilitating stroke. Other cardiovascular events were predefined as secondary outcomes.
The 3,825 patients randomized to nifedipine were comparable with the 3,840 randomized to placebo. The average age was 63.5 years, and 79 percent of participants were men. One half of the participants had experienced myocardial infarction, and one fourth had undergone a coronary revascularization procedure. Nearly 70 percent had significant lesions on coronary angiography, and 46 percent had NYHA classification of II or III. By six weeks, 88 percent of patients were taking the full dose of medication. Sixteen percent of patients reduced nifedipine to half-dose. Therapy was discontinued by 34 percent of patients taking nifedipine and 31 percent of those receiving placebo. The most common adverse events leading to discontinuation of nifedipine were peripheral edema and headache.
The mean follow-up achieved was almost five years. Patients taking nifedipine experienced significant increases in heart rate and reductions of blood pressure compared with the placebo group. Cardiovascular and noncardiovascular death rates were similar in the two groups. Patients treated with nifedipine had significant reductions in new overt heart failure, coronary angiography, and bypass surgery. Overall, nifedipine prolonged mean event-free survival by 41 days, mainly because of a reduction in coronary angiography.
The authors conclude that nifedipine is safe in patients with stable angina pectoris already using conventional treatments and is associated with a reduction in coronary procedures and interventions. The death rate in patients assigned to nifedipine was 1.1 per 1,000 patient-years greater than the placebo group, but most of these deaths were not because of cardiovascular causes. No evidence was found indicating that nifedipine induces myocardial infarction or heart failure.
Long-term potassium citrate therapy and bone mineral density in idiopathic calcium stone formers
Several authors have described an association between idiopathic calcium (Ca) stone disease and bone mass reduction. Hypocitraturia is a frequent feature of urolithiasis, and alkaline citrate has been recommended as one of the choice treatments in this disease. Some evidence exists as to the positive effect of potassium (K) citrate therapy on bone mass. The aim of this work was the longitudinal evaluation of bone mineral density (BMD) changes in a group of Ca oxalate stone formers treated with K citrate for two years. Enrolled patients were 120; 109 subjects completed the study (51 males and 58 females). A metabolic study and distal radius BMD measurements were conducted both at baseline (BAS) and at the end of the study (END). BMD (0.451 0.081 vs 0.490 0.080 g/cm2), T-score (-1.43 1.02 vs -0.90 1.04), net gastrointestinal alkali absorption (40.37 50.57 vs 61.26 42.26 mEq/day), urinary citrate (2.53 1.15 vs 3.10 1.44 mmol/day) and K (58.93 22.28 vs 65.45 23.97 mmol/day) excretion significantly increased from BAS to END. Urinary Ca excretion remained unchanged from BAS to END (5.16 2.74 vs 5.57 2.85 mmol/day). Our results indicate that long-term treatment with K citrate increases forearm BMD in idiopathic Ca stone formers. It seems probable that the alkali load provided by this drug reduces bone resorption by a buffering of the endogenous acid production. K citrate appears to be a further therapeutic opportunity for the management of osteoporosis in Ca stone formers.
Optimal dairy servings to meet calcium needs: learn why two to three servings of dairy products are not enough to meet the recommended intake of calcium
There is little disagreement about the public health benefits of adequate consumption of calcium. In addition to its importance to bone health early in life, the importance of calcium to maintain skeletal integrity across the life span is also well accepted. Low dairy food intake and thus, inadequate calcium intake in youth sets the stage for skeletal fragility later in life. This can result in osteoporosis and an increased risk of bone fracture. Osteoporosis is now recognized as a “pediatric disease with geriatric consequences” since more than 90% of peak bone mass is achieved by about age 20.
Dairy products have long been recognized its nutrient-dense foods due to their high-calcium content and bioavailability, high levels of other essential nutrients and relatively low cost. Getting adequate amounts of calcium and other nutrients from dairy has also been demonstrated to help reduce the risk of high blood pressure and colon cancer. Other potential benefits of calcium that have been reported include lowering the risk for kidney stones and premenstrual syndrome. And most recently, evidence is mounting that diets high in calcium and. in particular, from calcium-rich dairy foods, are effective in enhancing body weight and body fat loss in calorie-restricted diets.
The recognition by nutrition experts of calcium’s critical role in bone health contributed substantially to the Institute of Medicine of the National Academy of Sciences” decision in 1997 to increase calcium intake recommendations for adolescents, adults and adults more than 51 years of age. Unfortunately, national nutrition surveys show that few Americans are meeting the dietary recommendations for calcium intake.
While it is difficult to accurately estimate inadequate intake of calcium, currently, only about 32% of boys and 12% of girls aged 12 to 19 years consume the recommended amounts of calcium. In adult men and women 20 years and over, only 27% and 10.2%, respectively, meet recommended amounts of calcium. In the elderly 70 years and over. only 13% of men and 4% of women meet recommended calcium intakes. Clearly. Americans’ low calcium intake is recognized as a major public health problem and is identified its one of the priority nutrition problems in the United States.
Health professional organizations agree that conventional foods are the preferred source of calcium and that low-fat dairy products are the best sources of calcium. This is because not only are they rich in calcium, they also contain essential nutrients including protein, phosphorus, potassium, riboflavin, magnesium, zinc, and vitamins A, [B.sub.12] and D. which are all necessary lot optimal bone health and human growth and development. To help children, adolescents and adults meet their calcium needs, government education programs and health professional organizations including the American Heart Association, the American Academy of Pediatrics, the National Medical Association and Health Canada encourage up to four servings of milk throughout the day.
Milk matters more
The Dietary Guidelines for Americans–2000 recommends that Americans two years and older consume two to three dairy servings per day depending on age, with each serving supplying 3001rig calcium. These recommendations are based on idealized diets that were developed for the Food Guide Pyramid (FGP) using recommended dietary patterns that include significant amounts of non-dairy calcium (250-475mg pet day) derived from recommended intakes of vegetables, whole and enriched grams, fruits and meat. However, most Americans consume substantially less than the recommended servings of whole and enriched grains, dark-green leafy vegetables, legumes and fruit. For example, the FGP recommendations of four servings of dark-green leafy and deep yellow vegetables and legumes per day, for u 2,200 calorie diet is three to four times higher than current consumption by Americans two through 70 years of age and six to 8 1/2 times higher than current consumption by children two to 19 years old.
The suggested amounts of whole grains recommended for u 2,200 and 2,800 calorie diet are, on average five times higher than what Americans currently consume. Thus, while intake of vegetables, whole grains and fruits should be encouraged, it is highly unlikely, bused on current trends in vegetable and grain consumption, that Americans will get the amount of calcium from these sources as suggested by the FGP. The result: Recommended diets may end up exacerbating low calcium retake by promoting the intake of foods that are generally poor sources of calcium and that have a low probability of consumption, while limiting the intake of excellent sources like low-fat dairy products, which have a substantially greater probability of consumption.
Researching needed servings
Given the low consumption of whole grains, vegetables and fruit by Americans, it is unclear whether the actual calcium intake in persons who consume the FGP recommended two to three servings of dairy are meeting the recommended Adequate Intake (AI) of calcium established by the Institute of Medicine. Researchers have recently evaluated the “actual” consumption of calcium from non-dairy and dairy food sources using the Continuing Survey of Food Intake by Individuals (CSFII) and the National Health and Examination Survey (NHANES), two very large nationally representative dietary surveys that monitor the food and nutrient intakes of U.S. children, adolescents and adult men and women. Their findings were highly consistent between both surveys. The chart to the right shows the ideal number of dairy servings required to meet the AI for calcium for each age group.
These results indicate that the number of dairy servings recommended by the FGP should be increased by one serving for all age groups nine years old and greater in order to reduce the likelihood of inadequate intakes of calcium. These results also raise some important considerations for dietary recommendations. It is clear that the FGP recommends idealized diets and thus, if certain foods in the diet are not consumed us suggested, then the intake of certain nutrients may be low. For example, the Dietary Guidelines for Americans 2000 suggests that certain non-dairy sources (e.g., canned fish with bones, fortified orange juice, fortified soy beverage, tofu and some dark-green leafy vegetables) could be consumed to increase calcium in the diet. In CSFII, however, less than 0.2% of the foods consumed by Americans were derived from these items as compared to 10% for milk, cheese and yogurt. These data looked at actual food consumption and suggests that adding one additional serving of dairy products might be more effective for meeting calcium needs than trying to increase non-dairy foods sources. The critical need of dairy products to meet calcium needs is underscored in Healthy People 2010: Objectives for Improving Health. It states: With current food selection practices, use of dairy products may constitute the difference between getting enough calcium in one’s diet or not.
A growing body of literature also exists indicating that consumption of three to four servings of dairy foods per day may help to lower the risk of chronic disease conditions, many of which are costly as well as responsible for considerable morbidity and mortality.
For example, a considerable body of scientific evidence exists showing the beneficial effects of dairy food consumption on reducing blood pressure. The results of clinical studies suggest that the consumption of recommended levels of dairy products can contribute to lower blood pressure in individuals with normal and elevated blood pressure. The blood pressure-lowering effect of dairy products is best exemplified by the Dietary Approaches to Stop Hypertension (DASH) clinical trials. These studies demonstrated that at low-fat dietary pattern high in fruits and vegetables and dairy products produced greater reductions in systolic blood pressure and diastolic blood pressure than either at diet high in only fruits and vegetables or at control diet low in both dairy and fruits and vegetables.
Also, rapidly emerging research provides consistent support for a beneficial effect of increased dairy foods on body weight and fat loss. Recent clinical studies have demonstrated enhanced body weight/body fat loss can be achieved when adequate calcium is provided front calcium supplements but is further enhanced by dairy foods, indicating that additional nutrients from dairy foods are playing an important role. In all of these clinical studies the dietary (dairy) calcium intake was equivalent to three to four servings of dairy products (milk, cheese and yogurt) per day as part of a reduced-calorie diet.
No relationship found between calcium intake and body size in Pima Indians
Recent research has suggested that calcium intake may have a protective effect against obesity, with calcium from dairy products providing a greater ‘anti-obesigenic’ effect than supplemental sources of calcium. Early studies in animal models and cell culture noted a physiological influence of intracellular calcium on glucose transport, lipogenesis, and lipolysis, suggesting a role for calcium in obesity and diabetes.
Since the time of the animal studies, an inverse relationship between body weight and calcium intake has been observed in multiple studies. Due to these findings, advertising campaigns and Web sites promoting milk consumption as part of a weight-loss regimen have appeared. In contrast, an extensive review of the literature by Barr concluded, “there is little support for an effect of dairy products or calcium supplementation in reducing body weight or fat mass.”
The mechanism by which calcium may modulate body weight is yet unclear, however researchers hypothesize that increased intakes of dietary calcium result in decreased levels of intracellular calcium, triggering increased lipolysis. Conversely, low intake of dietary calcium may stimulate the release of circulating parathyroid hormone and 1,25-dihydroxyvitamin D, therefore increasing adipocyte intracellular calcium, and favoring lipogenesis.
As the prevalence of obesity in the United States has increased, the calcium intake from dairy products has decreased. The Pima Indian population of Arizona is highly prone to the development of obesity and diabetes, and since 1982 has participated in many National Institute of Health (NIH)conducted studies. A large-scale dietary survey of the Pima Indians found that most adults consumed at least two-thirds of the recommended dietary allowance for calcium, suggesting that this obesity-prone population was not markedly calcium deficient.
A recent study aimed to determine if calcium intake in Pima Indians was related to body weight and adiposity. Both children and adults were studied. Sixty-five adult Pima Indians and 78, healthy, Indian children participated.
All adult subjects were healthy. Height and body weight was measured and body composition was determined using dual-energy X-ray absorptiometry. Body mass index (BMI) was calculated. Daily nutrient intake by the adults during the previous year was assessed using the Block 1998 Food Questionnaire. The analysis of this questionnaire provided an assessment of total calcium intake but did not distinguish between dairy and nondairy sources of calcium. Children’s food intake was assessed by 24-hour recall.
There were significant (P = .0001), all) positive correlations between calcium intake and energy intake in the whole group (r = 0.69), and in men (r = 0.71) and women (r = 0.65) separately. Calcium intake was not significantly correlated with percentage of energy consumed as fat in the entire group or in men (r = -. 10, P = .43; r = -0.11, P = .53; respectively); however, in women there was a significant inverse association between calcium intake and percentage of energy as fat (r = -0.35, P = .05). The correlations between calcium intake and measures of weight and adiposity in the adults were not significant (body weight, r = 0.05, P = .71; body fat, r = -0.16, P =. 19; BMI, r = 0.01, P = .97). In children, there were not significant relationships between either calcium intake or estimated dairy intake and body weight (r = 0.04, P = .73; r = 0.03, P = .75, respectively), body fat (r = 0.07, P = .53; r = 0.09, P = .43, respectively), or BMI (r = 0.03, P = .78; r = 0.04, P = .71, respectively). In multiple linear regression models accounting for sex, age, and energy intake, calcium intake was not a significant determinant of BMI or adiposity in either adults or children.
Calcium intake-kidney stones
Recent studies offer conflicting advice about dietary calcium intake and its contribution to kidney stone formation. About 80% of all kidney stones are composed of calcium phosphate or calcium oxalate. The headline for a widely-publicized, 2005 press release from the University of Texas Southwestern Medical Center of Aging recommends restricting calcium intake. A 2004 study, however, that used data from the Nurses’ Health Study II found that women with a higher dietary calcium intake had less risk of developing kidney stones.
“UT Southwestern Researchers Find Calcium Intake Contributing Factor In Formation Of Kidney Stones” reads the headline for the university press release and corresponding article at www.sciencedaily.com. The article refers to two studies. The first looks at formation of calcium oxalate stones and appears in Kidney International (November 2004). The other focuses on calcium phosphate stones and appears in the Journal of Urology (December 2005). Both conclude that “urinary calcium–the amount of calcium in a person’s urine–is an important contributing factor in the formation of both types of kidney stones.” Both studies use data from UT South western’s kidney stone registry: 667 patients with predominantly calcium oxalate stones for the first and 133 patients with predominantly calcium phosphate stones for the second. Using “a newer, lower stability constant [mathematical formula],” the researchers found that urinary calcium is as important as oxalate or phosphate in kidney stone formation. However, neither study looked specifically at how much calcium the patients actually consumed. Several conditions lead to increased blood levels of calcium (affecting urinary calcium levels), including primary parathyroid dysfunction, sarcoidosis, hyperthyroidism, and renal tubular acidosis. Yet, two of the authors quoted in the press release take the leap that people with stones “may need to carefully monitor their calcium dietary intake.”
In the 2004 study, Gary C. Curhan, MD, ScD, and colleagues examined dietary factors and risk of kidney stone among 96,245 female nurses (age 27 to 44 years) in the Nurses’ Health Study II (Arch Intern Med. 2004; 165:885-891). None of these women had a history of kidney stones. The researchers documented the development of 1,223 kidney stones over an eight-year period. “Women who consumed the most calcium (top 20% of calcium intake) had a 27% lower risk of developing kidney stones compared to women who reported consuming the least amount of calcium (lowest 20% of calcium intake).”
In the Background section of the Nurses’ Health Study II article, Curham and colleagues said that previous studies involving older women and men showed that “greater intakes of dietary calcium, potassium, and total fluid reduce the risk of kidney stone formation, while supplemental calcium, sodium, animal protein, and sucrose may increase the risk.” This study, involving younger women, showed no association between calcium supplementation and kidney stone risk. The researchers also found that “[w]omen who consumed the most phytate (top 20% of phytate intake) in the study group had a 37% lower risk of developing kidney stones compared to women who consumed the least amount of phytate (lowest 20% of phytate intake).” Phytate inhibits mineral absorption and is found in whole grains, pulses (peas, beans, lentils), and soy beans.
Coral Calcium Greatest Advantage
Calcium is one of the minerals that are good for the bones and are said to be able to treat some diseases such as diabetes, Alzheimer’s, lupus and cancer. However there are no research studies that have proven that coral calcium is capable of treating diseases better than other carbonated calcium pills which are not expensive.
Coral calcium became widely popular in the internet and health stores lately; however coral calcium pills are the most high priced in the history of pills.
Manufacturers claim that coral calcium is beneficial for treating almost two hundred kinds of diseases and also good for relieving pain. Advertisements and some websites are announcing that coral calcium cures cancer. They site a situation in Okinawa Japan where people who lives there are having a longer life span because the water that they are drinking has high level contents of coral calcium. Coral calcium is making the water into alkaline and it balances the acidity of the body in an individual. So coral calcium are good for acidic persons but be aware that you may experience some difficulties upon swallowing the pills if your acidity body contents are similar as the acidity in the labels imply.
Coral calcium is made out of corals and other sea creature’s shells having higher contents of calcium carbonate and other minerals including magnesium.
Coral calcium is a dietary supplement so it is unregulated. People should learn that such products could not be safe even if its manufacturers are claiming its benefits. As history tells about supplements, there are basically some that has calcium contents that have found out to be unsafe thus some of them was tested to have higher lead contents which are health hazards.
Coral calcium alone cannot fight diseases. It must be combined with drinking mineral or spring water rich in oxygen and higher pH factor and other minerals or elements providing the natural ability of the body to fight back diseases.
Coral calcium is good for increasing the level of oxygen in the body helping it to get rid of toxicity build up. If you are a keen observer, you can determine the feeling of being sluggish after eating junk food or a heavy meal. It is because the oxygen are diverted away from the body’s main metabolic functions making it hard to digest high calories.
Coral calcium offered the greatest advantage of balancing the pH alkaline level in the body in helping the system of the body fight or prevent diseases from attacking.
What Is Coral Calcium?
Corals are tiny marine animals correlated to the sea life. They live in the form of skeletal polyps known as hermatypic corals and stony corals, which have an external skeleton of calcium carbonate. Polyps are clones, which grow on the skeletal remains of past generations of Polyps. They collectively form a coral head. Corals are typically found living in colonies formed by hundreds of individual polyps. Stony corals living together as a group are generally known as coral reefs. Coral reefs are derivatives of the accumulated coral skeletal remains. Coral reefs take particular shapes because of wave patterns and varying temperatures of land and water, which are vital for its survival.
Salts of calcium that are obtained from fossilized coral reefs are known as coral calcium. Coral calcium is acquired by grinding up limestone, which is found above the ground and was once part of the coral reef. Living coral reefs cannot be harvested because they are endangered.
Calcium carbonate, small amounts of magnesium, and other trace minerals together constitute the Coral calcium. Despite the claims of some companies selling this product, the calcium carbonate obtained from coral reefs is chemically identical to other sources of the chemical.
Coral calcium may contain trace minerals that may be helpful to the humans who are deficient in them. The calcium that is offered by the corals is indistinguishable to any other limestone. Many theories regarding corals have been propagated even though no solid evidences are available to support them. The recent humors regarding coral calcium are that it can cure cancer by increasing body pH. Scientists have proven that cancer cells cannot survive at high pH levels. However, it is yet to be confirmed whether the coral calcium only neutralizes the pH levels or actually causes damage to other healthy body cells as well.
Even though coral calcium may be helpful for the body, individuals have other sources of calcium to avail of. Individuals should not entirely depend on coral calcium as it is depleting and it will soon become extinct if its usage is not curbed.
Calcium and Alkalinity, pH, Salinity and Magnesium
To the new hobbyist, these terms can be rather intimidating. And when you are trying to consider the relative effects of each on the other, it can become quite confounding. I will try and cover some of the basic elements of the interaction of these elements as it relates to calcium. PH is simply a measure of the relative balance of hydroxide and hydrogen ions in water. In layman’s terms, this means that there are hydroxide elements and hydrogen elements in the water. In a particular solution, whatever the balance is in these two elements determines the “pH”. PH is measured on a scale from 0 to 14, with the midpoint, 7 being described as “neutral”. Solutions with a pH measurement above 7 are considered “base”, while those below 7 are considered “acidic”. Seawater pH is typically 8.0 - 8.5, and is therefore somewhat “base”. Another thing to note about pH, is that the scale is logarithmic. This means is that each gradation represents a factor of ten. So a pH of 8 is 10 times more base than 7, and 9 is 100 times more base than 7, and so on.
What is important about all this is that small changes in pH are very significant to tank inhabitants and to calcium levels. With all things being equal, the higher the pH of the water, the less calcium the water will hold “in solution”. This is not generally a problem as long as the hobbyist keeps the tank pH within the prescribed range, 8.0 - 8.5. However, some methods of adding calcium will affect aquarium pH, which is why it is important to understand the relationship of calcium and pH.
Alkalinity, in short, is the water’s ability to withstand additions of acids, without changing the pH. Other terms that are commonly used to describe alkalinity include buffer or buffering, DKH, meq./ltr., and carbonate hardness. For all practical purposes, they are all the same thing (there are some slight differences in some, but not enough for our purposes here). The elements that provide this effect are carbonates, mostly sodium carbonate and sodium bicarbonate. Alkalinity is necessary in the aquarium to help guard against large swings in pH, which will stress the tank inhabitants. Recommended levels range from 7 dkh to 12 dkh. The other commonly used scale to measure alkalinity is meq./ltr (read as megaequivalents per litre). To convert dkh to meq./ltr you simply divide by 2.8. Relative to calcium, the higher the dkh, the less calcium that will stay in solution. So long as alkalinity is kept in the acceptable range, this should not hinder achieving proper levels of calcium. But, like pH, some calcium additive methods affect alkalinity, thus this basic understanding.
I would also like to refer those who are curious about the calcium/alkalinity dance to an article written by Craig Bingman (Aquarium Frontiers on-line, July 1998). This is an excellent discussion of the relationship between alkalinity and calcium, and recommendations regarding simulating natural seawater levels of both components.
Salinity is another factor in calcium concentrations. The above calcium recommendations are at full strength seawater with a specific gravity of 1.025. If the aquarium is kept at a lower specific gravity, then a given concentration of calcium measured in the water will really be at a higher relative concentration to the other water elements. Put simply, if your tank is run at lower than full strength seawater levels, then the required concentration of calcium will also be proportionally lower.
Magnesium is another player in the dance with calcium. Magnesium levels are typically pretty stable in the aquarium, and are easily maintained with routine water changes. However, if calcium precipitation occurs, or the hobbyist does not do regular water changes, magnesium levels can decline. The recommended level of magnesium in the aquarium is 1300 ppm to 1500 ppm. If magnesium levels do fall, calcium has been found to be much more difficult to get to the proper levels of concentration. However, I want to emphasize that when the hobbyist encounters difficulty maintaining calcium levels, it is best to rule out all other causes before considering magnesium deficiency. This is simply because it is far more often the case that other factors are at play in the problem. If it is suspected that magnesium deficiencies are a problem, it is recommended that a magnesium test kit be purchased and used to verify the problem. Magnesium supplements are readily available, and replenishment can also be accomplished through the use of Epsom Salts.
Calcium for Dummies
As a reefkeeper over the past 12 years or so, I found the topic of calcium additions to be one of the most challenging and confusing to learn and master. I found a large body of information available, and many, many products that made claims to help increase and maintain calcium levels in the aquarium. Unfortunately, some of it was conflictual and most of it was very difficult for me to understand. So, I write this article with the intent of helping other hobbyist to learn what I’ve learned regarding calcium additions to the marine aquarium reef tank. Let me begin by saying that I am not a chemist. Indeed, (and this may become obvious), I have not even attended a chemistry class of any kind. This is a distinct weakness in that my understanding of the complex chemical interactions involved in water parameters for the reef aquarium has been slow to advance, and is still far from complete. However, it may be a strength in that I may be able to explain, in layman’s terms, some important concepts involved in the use of calcium in the reef tank. To those of you who are more chemically knowledgeable, I apologize for my overly simplistic terms and descriptions. To those of you just learning these concepts, I hope I can be of some help. It is my intent to use plain language, as much as is possible, so that even the newest of hobbyist can use this information in deciding how to add calcium to their own system.